Optical Coherence Tomography (OCT) is a non-invasive optical technique for cross-sectional imaging of biologic tissues which permits identification of both internal structure and surface contour of hard and soft tissues without ionizing radiation. Based on previously sponsored efforts, the authors have designed and constructed an OCT instrument for imaging teeth and periodontal tissues. Initial human studies demonstrate the feasibility of this method. The goal of this proposal is to construct a small, compact clinical instrument that will allow access to all tooth-bearing regions within the oral cavity. The capacity of OCT to characterize morphology, localize structures and quantify sub-gingival calculus will be determined in a small patient study. The authors hope to identify OCT signals associated with periodontitis and/or gingivitis. In order to make the device clinically relevant., the authors propose to optimize the instrument and evaluate its performance in comparison to standard techniques. The specific aims of the proposal are to (1) construct an improved, miniaturized intraoral OCT imaging hand piece; (2) miniaturize OCT imaging system components; (3) image and characterize healthy and diseased periodontal tissue and optimize OCT imaging parameters; (4) compare OCT imaging to standard assessment methods; and (5) investigate the potential of OCT to quantify gingival inflammation. Images produced to date suggest that OCT may delineate pathological changes in gingival fiber groups based on changes in optical properties. Finally operating OCT systems at multiple wavelengths may be used for quantification of blood and fluid content in tissue. This project is carried out in conjunction with Lawrence Livermore National Laboratory.